Wafer edge cleaning

ABSTRACT

In a first aspect, an apparatus for cleaning a thin disk is provided. The apparatus includes a support roller for supporting a rotating wafer within a wafer cleaner. The support roller comprises a guide portion, for receiving an edge of a wafer, having an inclined surface comprising a low-friction material and adapted to allow the wafer edge to slide thereagainst; and an edge-trap portion for retaining the edge of the wafer and having a transverse surface comprising a high-friction material and adapted, when in communication with the edge of the wafer, to resist sliding thereagainst. Numerous other aspects are provided.

This application is a division of, and claims priority to, U.S.Non-Provisional patent application Ser. No. 10/976,011, filed Oct. 28,2004, and titled “WAFER EDGE CLEANING” (Attorney Docket No. 8186), whichclaims priority to U.S. Provisional Application Ser. No. 60/514,938,filed Oct. 28, 2003, and titled “WAFER EDGE CLEANING” (Attorney DocketNo. 8186/L). Both of these patent applications are hereby incorporatedby reference herein in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates generally to cleaning thin disks, such assemiconductor wafers, compact disks, glass substrates and the like. Moreparticularly, the invention relates to scrubbing devices forsimultaneously scrubbing the entire surface of a thin disk, includingthe edges thereof.

BACKGROUND OF THE INVENTION

To manufacture a thin disk such as a semiconductor wafer, an elongatedbillet of semiconductor material is cut into very thin slices or disks,about 2 mm in thickness. The slices or wafers of semiconductor materialare then lapped and polished by a process that applies an abrasiveslurry to the wafer's surfaces. After polishing, slurry residueconventionally is cleaned or scrubbed from wafer surfaces via amechanical scrubbing device, such as a device which employs polyvinylacetate (PVA) brushes, brushes made from other porous or sponge-likematerial, or brushes having bristles made from nylon or similarmaterials. Although these conventional cleaning devices remove asubstantial portion of the slurry residue which adheres to wafer edges,slurry particles nonetheless may remain and produce defects duringsubsequent processing.

A conventional PVA brush scrubber is shown in the side elevational viewof FIG. 1. The conventional scrubber 11, shown in FIG. 1, comprises apair of PVA brushes 13 a, 13 b, a platform 15 for supporting a wafer W,and a mechanism (not shown) for rotating the pair of PVA brushes 13 a,13 b. The platform 15 comprises a plurality of rollers 17 a-c for bothsupporting and rotating the wafer W.

Preferably, the pair of PVA brushes 13 a, 13 b are positioned to extendbeyond the edge of the wafer W, so as to facilitate cleaning the wafer'sedge. However, research shows that slurry induced defects still occur,and are caused by slurry residue remaining along the edges of the waferdespite cleaning with apparatuses such as that described above.Specifically, subsequent processing has been found to redistributeslurry residue from the wafer edges to the front of the wafer, causingdefects.

A number of devices have been developed to improve wafer edge cleaning.One such device is shown in the side elevational view of FIG. 2. Theedge-cleaning scrubber 19, shown in FIG. 2, includes a pair of rollers17 b, 17 c adapted to support and rotate the wafer W, and furtherincludes an edge-cleaning roller 21 that fits over the edge of the waferW for cleaning the edge as the wafer rotates. Although the edge-cleaningroller 21 addresses the need to clean slurry residue from wafer edges,it can be subject to quick wear, such wear typically being concentratedat locations where it contacts the wafer W.

FIGS. 3A-3C illustrate details related to how the edge-cleaning roller21 of the edge-cleaning scrubber 19 of FIG. 2 cleans the edge of thewafer W. Referring to the side elevational view of FIG. 3A, which showsthe wafer W above the edge-cleaning roller 21, the edge-cleaning roller21 of FIG. 2 is shown in contact with the wafer W. Specifically,opposing first and second inclined surfaces 23, 25 of the edge-cleaningroller 21 are in contact with respective opposite first and second edgecorners 27, 29 of the edge of the wafer W. For example, either or bothof the first and second edge corners 27, 29 may comprise a bevel so asto form, e.g., a truncated frustoconical edge surface (not separatelyshown) which may be placed in surface-to-surface contact with the firstand second inclined surfaces 23, 25 of the edge cleaning roller 21.

Referring to the side elevational view of FIG. 3B, in which the wafer Wis shown in phantom across the edge-cleaning roller 21, the wafer Wrotates in a nominal rotation plane 31, as does the edge-cleaning roller21. By “nominal rotation plane” is meant that plane within which thewafer W is expected to rotate based on the specific arrangement ofrollers (e.g., the rollers 17 b, 17 c) used to support, drive and guidethe wafer W within the edge-cleaning scrubber 19 of FIG. 2. Further, itmay be seen that contact between inclined surfaces 23, 25 of theedge-cleaning roller 21 and the first and second edge corners 27, 29 ofthe wafer W takes place along respective first and second contact areas33, 35 on the inclined surfaces 23, 25.

Referring to the cross-sectional view of the edge-cleaning roller 21shown in FIG. 3C, corresponding to section 3C-3C as shown on FIG. 3B,the first contact area 33 on the first inclined surface 23 translates toa ring-shaped wear sector 37 on the first inclined surface 23, typicallyrelatively narrow, which performs the edge-cleaning function and issubject to friction-induced wear over time. Conversely, the remainingportions of the first inclined surface 23 may not typically contact thewafer W during edge cleaning, and therefore may not be subject to suchfriction-induced wear.

Other rollers that may rotate in a common plane with a wafer W whilecontacting a portion of the wafer edge, but that perform additional orseparate functions such as rotating the wafer W (e.g., drive rollers,such as the spinning mechanism 17 a-c of FIG. 1) or guiding the rotatingwafer W so as to limit or prevent tilting of the same (e.g., idlingguide rollers (not separately shown)), are typically also subject torapid wear where contact is made with the wafer W. The cost ofmaintaining proper operation of such parts and/or conducting frequentreplacement of the same can mount quickly.

Accordingly the field of wafer cleaning requires methods and apparatusfor effectively performing one or more of the functions of cleaning,supporting, driving and guiding both the flat surfaces and the edgesurfaces of a semiconductor wafer, preferably so as to reduce the costand/or frequency of replacement due to frictional wear from wafercontact.

SUMMARY OF THE INVENTION

The present invention addresses the need for a more effective edgecleaner by providing a number of different roller embodiments that areadapted for wafer edge cleaning. Specifically:

-   -   (1) for cleaning the edge bevel of a wafer, an edge cleaning        roller is adapted to rotate within a plane that is at an angle        to a first plane in which the wafer is supported and rotated;    -   (2) for cleaning the circumferential edge of a wafer, an edge        cleaning roller is provided with a flat-bottomed channel having        a frictional surface along the channel's bottom; and/or    -   (3) for cleaning an edge region of a major surface of a wafer,        an edge cleaning roller is provided with a straight-walled        channel having a frictional surface along at least one of the        straight walls thereof.

In a first aspect of the invention, an apparatus for cleaning a thindisk is provided. The apparatus includes (1) a plurality of supportrollers adapted to support an edge of the thin disk as the thin diskrotates within a first plane; and (2) an edge-cleaning roller adapted torotate within a second plane oriented at a first non-zero angle to thefirst plane, so as to contact an edge bevel of the thin disk while sorotating.

In a second aspect of the invention, a support roller is provided forsupporting a vertically rotating wafer. The support roller includes (1)a guide portion, for receiving an edge of a wafer, having an inclinedsurface comprising a low-friction material and adapted to allow thewafer edge to slide thereagainst; and (2) an edge-trap portion forretaining the edge of the wafer and having a transverse surfacecomprising a high-friction material and adapted, when in communicationwith the edge of the wafer, to resist sliding thereagainst.

In a third aspect of the invention, a side-contact roller is providedfor contacting one or more major surfaces of a rotating wafer. Theside-contacting roller includes (1) a guide portion, for receiving anedge of a wafer, having an inclined surface comprising a low-frictionmaterial and adapted to allow the wafer edge to slide thereagainst; and(2) an edge-trap portion for retaining the edge of the wafer and havinga planar surface comprising a high-friction material and adapted, whenin communication with a major surface of the wafer, to resist slidingthereagainst. Numerous other aspects, as are methods in accordance withthese and other aspects of the invention.

Other features and aspects of the present invention will become morefully apparent from the following detailed description, the appendedclaims and the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side elevational view of a conventional PVA brush scrubber.

FIG. 2 is a side elevational view of a conventional scrubber comprisinga conventional edge-cleaning roller for improving wafer edge cleaning.

FIG. 3A is a side elevational view of the edge-cleaning roller of FIG.2, shown cleaning the edge corners of the wafer W.

FIG. 3B is another side elevational view of the edge-cleaning roller ofFIG. 2, shown contacting the wafer W along contact areas on respectiveinclined surfaces of the edge-cleaning roller.

FIG. 3C is a cross-sectional view, corresponding to view 3C-3C of FIG.2, of the edge-cleaning roller of FIG. 2 showing a relatively narrowwear sector on an inclined surface of the edge-cleaning roller wherecontact is made with an edge corner of the wafer W.

FIG. 4 is a side elevational view of an inventive edge-cleaning roller,shown contacting edge corners of the wafer W and in an inventive angledorientation to a plane of rotation of the wafer W.

FIG. 5A is a view, corresponding to view 5A-5A of FIG. 4, of a majorsurface of the wafer W showing separate radial locations at which theinventive edge-cleaning roller of FIG. 4 contacts respective edgecorners of the wafer W.

FIG. 5B is a cross-sectional view, corresponding to view 5B-5B of FIG.4, of the inventive edge-cleaning roller of FIG. 4 showing a relativelywide wear sector on an inclined surface of the edge-cleaning rollerwhere contact is made with an edge corner of the wafer W.

FIG. 6A is a side elevational view of an inventive edge-cleaning supportroller, shown in contact with a cylindrical edge surface of the wafer W.

FIG. 6B is an exploded assembly perspective view of an edge-cleaningsupport roller that is a particular embodiment of the inventiveedge-cleaning support roller of FIG. 6A.

FIG. 7A is a side elevational view of an inventive edge-cleaningside-contact roller, shown engaging the edge of the wafer W.

FIG. 7B is a cross-sectional view of an edge-cleaning side-contactroller that is a particular embodiment of the inventive edge-cleaningside-contact roller of FIG. 7A.

FIG. 8 is a side elevational view of an inventive edge-cleaning roller,shown contacting edge corners of the wafer W and in another inventiveangled orientation to a plane of rotation of the wafer W.

FIG. 9 is a side elevational view of two inventive edge-cleaning rollersof FIG. 8, shown contacting edge corners of the wafer W and in oppositeinventive angled orientations to a plane of rotation of the wafer W.

DETAILED DESCRIPTION Edge Cleaning Roller

FIG. 4 is an side elevational view of an inventive edge-cleaning roller101 in which the wafer W is shown in phantom across the edge-cleaningroller 101, the edge-cleaning roller 101 being adapted to contact edgesurfaces (e.g., edge bevels as described above with reference to FIG.3A) of the wafer W for cleaning. Where, as described above, the wafer Wis supported and driven so as to rotate and remain within the nominalrotation plane 31 of the wafer W (rotation and support means for thesame not being shown), the edge-cleaning roller 101 may be inventivelyoriented relative to the wafer W so as to form a first angle 103, thefirst angle 103 being that angle which is described between the nominalrotation plane 31 of the wafer W and a rotation plane 105 within whichthe edge-cleaning roller 101 is disposed and is adapted to rotate.

As shown in FIG. 4, the rotation plane 105 of the edge-cleaning roller101 may be oriented relative to the nominal rotation plane 31 of thewafer W such that, in forming the first angle 103, the rotation planesintersect along a line (not separately shown) generally extendingradially outward from the center of rotation of the wafer W. Otherrelative orientations are possible, such as a relative orientationbetween the rotation planes whereby the planes intersect along a linegenerally extending tangentially to the wafer W, as is illustrated inFIGS. 8 and 9 and as will be described later.

Referring again to FIG. 4, the edge-cleaning roller 101 may compriseopposing first and second inclined surfaces 107, 109 which contact therespective opposite first and second edge corners 27, 29 (FIG. 3A) ofthe edge of the wafer W. By contrast to the pattern of contact betweenthe wafer W and the edge-cleaning roller 21 as shown above in FIGS. 3Aand 3B, e.g., in which both the first and the second edge corners 27, 29of the wafer W are contacted by the edge-cleaning roller 21 atsubstantially the same radial location along the perimeter of the waferW, the inventive angled orientation of the edge-cleaning roller 101relative to the wafer W shown in FIG. 4 may result in divergent radialcontact locations along the perimeter of the wafer W. For example, asshown in the planar view of a major surface of the wafer W shown in FIG.5A (corresponding to the view 5A-5A of FIG. 4), contact between thefirst inclined surface 107 (FIG. 4) of the edge-cleaning roller 101 andthe first edge corner 27 of the wafer W may occur at a first radiallocation 111 along the perimeter of the wafer W, contact between thesecond inclined surface 109 (FIG. 4) of the edge-cleaning roller 101 andthe second edge corner 29 of the wafer W may occur at a second radiallocation 113 along the perimeter of the wafer W, and a second angle 115separates the first radial location 111 and the second radial location113.

Referring again to FIG. 4, the inventive angled orientation of theedge-cleaning roller 101 relative to the wafer W may result in a longeruseful life for the edge-cleaning roller 101. For example, where inFIGS. 3A and 3C it is shown that coplanar orientation between therespective rotation planes of the edge-cleaning roller 21 and the waferW may result, as mentioned above, in a relatively narrow ring-shapedwear sector 37 on the first inclined surface 23 of the edge-cleaningroller 21, the inventive angled orientation of FIG. 4 may increase wearsector width, thus distributing the edge-cleaning function over largercontact areas (see 121, FIG. 5B) on the inclined surfaces of theedge-cleaning roller 101. The inventive angled orientation of FIG. 4therefore may increase the wafer's edge cleaning duty cycle and mayextend the useful life of the roller 101.

FIG. 5B, which is a cross-sectional view of the edge-cleaning roller 101taken along a section 5B-5B of FIG. 4, illustrates the above-describedfeature. Referring to FIG. 5B, contact between the first inclinedsurface 107 of the edge-cleaning roller 101 and the edge of the wafer W(shown in phantom) at the first edge corner 27 (FIG. 3A) of the wafer Wtakes place along a first contact area 117 on the first inclined surface107, and a ring-shaped wear sector 119 on the second inclined surface109 may be produced thereby (e.g., by virtue of the rotation of theedge-cleaning roller 101) having a characteristic width 121.

As shown in FIG. 5B, the first contact area 117 tends to extend not onlylaterally across the slope of the first inclined surface 107, e.g.,similarly to the first contact area 33 of FIG. 3C, but also up the slopeof the first inclined surface 107, e.g., in contrast to the firstcontact area 33 of FIG. 3C. It may readily be seen, therefore, that thewidth 121 of the ring-shaped wear sector 119 on the first inclinedsurface 109 of the edge-cleaning roller 101 may be proportionatelygreater than a corresponding dimension (not separately shown) of thewear sector 37 on the first inclined surface 23 of the edge-cleaningroller 21 of FIGS. 3A-3C. Given a greater wear sector width, it followsthat the area of the first inclined surface 107 subjected tofriction-induced wear during wafer edge cleaning (i.e., the wear sectorarea) will be proportionately greater.

Assuming the degree of edge cleanliness required by the process remainsthe same, providing a greater area for the ring-shaped wear sector 119as described above can reduce the edge-cleaning burden per unit area ofthe wear sector, which may result in a longer useful life for theedge-cleaning roller 101. For example, given a larger portion of thefirst inclined surface 107 of the edge-cleaning roller 101 is being usedto clean the first edge corner 27 of the wafer W, edge cleaning may bemore efficient, thus allowing, e.g., the length of time that the firstinclined surface 107 is applied to the first edge corner 27 of the waferW to be decreased, or the contact pressure between the same to bereduced, while still producing the required degree of wafer edgecleanliness. Those possessing skill in the art will recognize that thesame dynamic exists between the second edge corner 29 (FIG. 3A) of thewafer W and the second inclined surface 109 (FIG. 4) of theedge-cleaning roller 101, resulting in a similar beneficial broadeningof a corresponding wear sector (not separately shown), and the samebenefits as to part life.

Those possessing skill in the art will also recognize that additionalflexibilities may be obtained by dividing edge-cleaning contact betweenthe edge-cleaning roller 101 and the wafer W between radiallyspaced-apart locations on the edge of the wafer W, e.g., as shown inFIG. 5A. For example, in some embodiments of the edge-cleaning roller101, a third angle 123 (see FIG. 4) described between the first inclinedsurface 107 and the second inclined surface 109 may be provided that iswider than is typical for edge-cleaning rollers, e.g., so as to morereadily facilitate rotation of the rotation plane 105 of theedge-cleaning roller 101 relative to the nominal rotation plane 31 ofthe wafer W. Nevertheless, despite the wider third angle 123, therespective effective angles of contact (not shown) between the firstinclined surface 107 and the second inclined surface 109 relative to thenominal rotation plane 31 of the wafer (e.g., as measured along theslope of the first inclined surface 107 normal to the direction alongwhich the scrubber 117 extends, and along the slope of the secondinclined surface 109 in a corresponding direction) may be controlled soas to be equivalent to those of typical edge-cleaning rollers.

Alternatively, if it is desired to increase the wafer's edge cleaning“duty cycle”, e.g., that angular fraction of the wafer's perimeter whichis in contact with the inclined surfaces 107, 109 of the edge-cleaningroller 101 at any given time, or if it is desired to increase the sizeof an area of edge-cleaning contact on one or more edge surfaces of thewafer W, the same angles of contact may be reduced below that which istypical, in effect narrowing the angular gap between the inclinedsurfaces 107, 109 of the edge-cleaning roller 101 and the major surfacesof the wafer W. This may be accomplished without undue risk of causingthe edge of the wafer to become wedged between the inclined surfaces ofthe edge-cleaning roller 101 and the rotation of the wafer W to becomeimpeded thereby, e.g., since an angular space exists in the form of thesecond angle 115 between the first and second radial locations 111, 113(FIG. 5A) along the perimeter of the wafer W at which contact with theinclined surfaces 107, 109 of the edge-cleaning roller 101 takes place.

Many different angles may be specified for the third angle 123. Forexample, applicants observe that an angle of 70 degrees, ±10 degrees,produces a good result.

The edge-cleaning roller 101 may further include a normal surface 125(FIG. 4), e.g., cylindrical in shape, and occupying a space between theinclined surfaces of the edge-cleaning roller 101. Such a space may beintroduced so as to facilitate the rotation of the edge-cleaning roller101 relative to the nominal rotation plane 31 of the wafer W. Althoughmany different widths may be specified for such a space, includingwidths of up to 10 mm or more, applicants observe that a dimension of 2mm, ±1 mm produces a good result. In addition, the normal surface 125 inthat space may or may not be disposed directly adjacent to the inclinedsurfaces. For example, the normal surface 125 may comprise a bottomsurface of a channel disposed in a space between the inclined surfaces(see, e.g., FIG. 4).

In some modes of use of the edge-cleaning roller 101, the normal surface125 is spaced apart from a cylindrical edge surface 39 (FIG. 3A) of thewafer W while the first inclined surface 107 and the second inclinedsurface 109 of the edge-cleaning roller 101 clean the edge corners 27,29 of the wafer W. In other modes of use of the edge-cleaning roller101, the normal surface 125 may be caused to contact and/or supportand/or clean the cylindrical edge surface 39 of the wafer W.

In addition, applicants observe that beneficial edge cleaning may beprovided where the first angle 103 described between the rotation plane105, within which the edge-cleaning roller 101 is disposed, and thenominal rotation plane 31 (FIG. 3B) of the wafer W, ranges from 10-30degrees. Optionally, therefore, the first angle 103 may be set at 15degrees, which applicants observe produces a good result.

Values of (1) a width of the space between the first inclined surface107 and the second inclined surface 109, (2) the third angle 123, and(3) the first angle 103 may be established/selected via an iterative,coordinated design process, so as to produce the desired interactionbetween the edge-cleaning roller 101 and the wafer W. Alternatively,selection of such values may be performed automatically based on thedesired result. Respective values of 3 mm, 50 degrees, and 20 degreesfor those three values provide a good result.

Furthermore, if desired, a slight torque may be introduced, e.g., toincrease a frictional cleaning pressure between the inclined surfaces107, 109 of the edge-cleaning roller 101 and the edge corners 27, 29(FIG. 3A) of the wafer W. In some embodiments, such a torque serves toincrease an area of the edge of the wafer W to be cleaned by theedge-cleaning roller 101, without undue risk of the wafer's edge beingpinched between the inclined surfaces of the edge-cleaning roller 101and thus without wafer rotation tending to be inhibited thereby.

In operation, the wafer W may be inserted between the first inclinedsurface 107 and the second inclined surface 109 of the edge-cleaningroller 101, placed in contact with same, e.g., according to the patternof FIG. 5A, and rotated in the nominal rotation plane 31 (FIG. 3B). Forexample, the wafer may be inserted between the first inclined surface107 and the second inclined surface 109 of the edge-cleaning roller 101with the rotation plane 105 of the edge-cleaning roller 101preliminarily in a coplanar relationship with the nominal rotation plane31 of the wafer W, and the edge-cleaning roller 101 may thereafter berotated to achieve the desired first angle 103. Alternatively, the firstangle 103 may be established prior to the wafer W being introduced tothe edge-cleaning roller 101.

As mentioned above, the edge-cleaning roller 101 may be utilized in amode in which contact with the wafer W is restricted to the firstinclined surface 107 and the second inclined surface 109. Alternatively,and as also mentioned above, the cylindrical edge surface 39 of thewafer W may also be made to contact a normal surface 125 (FIG. 4) of theedge-cleaning roller 101 at one or more times, e.g., either before orduring wafer edge cleaning, or before or during rotation of theedge-cleaning roller 101.

Where sliding contact is intended between the edge-cleaning roller 101and the wafer W, the surfaces of the edge-cleaning roller 101 involvedmay be adapted so as to further improve cleaning through greaterfriction. For example, such surfaces may comprise polyurethane, or someother suitable frictional material.

Additionally, edge surfaces of the wafer W and frictional surfaces ofthe edge-cleaning roller 101 may be caused to rotate at differentvelocities so as to enhance sliding contact. For example, the speed ofrotation of the edge-cleaning roller 101 may be controlled via aseparate motor, e.g., so as to cause the normal surface 125 to rotate ata different velocity than the cylindrical edge surface of the wafer W itcontacts. Also for example, the speed of the edge-cleaning roller 101may be selectively retarded (e.g., with a brake) if the wafer W itselfis used to drive the edge-cleaning roller 101.

Where the edge corners 27, 29 (FIG. 3A) of the wafer W comprise edgebevels, the first and second inclined surfaces 107, 109 of theedge-cleaning roller 101 may be angled and disposed so as to increase anarea of the edge bevels of the wafer W contacted/cleaned by the inclinedsurfaces. For example, the effective angles described between theinclined surfaces along the areas of contact described above and thenominal rotation plane 31 of the wafer W can be controlled so as tomaximize contact with the edge bevels.

Additional Edge-Cleaning Rollers

FIGS. 6A, 6B, 7A and 7B illustrate additional rollers adapted to achievefrictional contact with the edge of the wafer W, e.g., for purposes ofdriving or supporting the wafer W, and/or for preventing tilting thereofduring rotation. It will be understood, also, that where the rollers ofFIGS. 6A-B and 7A-B achieve frictional contact with the edge of thewafer W, edge cleaning of the wafer may also take place, such that therollers may also be denominated edge-cleaning rollers, e.g., either bydesign, or by virtue of how they are used in conjunction with a waferedge.

Unlike the edge-cleaning roller 101 of FIGS. 4 and 5A-B, which isadapted to achieve frictional contact with edge corners (or edge bevels)27, 29 (FIG. 3A) of the wafer W, the rollers of FIGS. 6A-B and 7B areadapted to achieve frictional contact with edge surfaces of the wafer Wthat may be adjacent to the edge corners 27, 29. For example, the rollerof FIGS. 6A-B is adapted to achieve frictional contact with thecylindrical edge surface 39 (FIG. 3A) between the edge corners 27, 29,and the roller of FIGS. 7A-B is adapted to achieve frictional contactwith one or both of a first edge-adjacent region 41 (FIG. 3A) of a firstmajor surface 43 (FIG. 3A) of the wafer W, and a second edge-adjacentregion 45 (FIG. 3A) of a second major surface 47 of the wafer W (FIG.3A). Additionally, the rollers of FIGS. 6A-B and 7A-B may compriseeasily replaceable frictional components adapted to bear the greaterportion of friction-induced wear where such frictional contact betweenthe rollers and the wafer W is intended to occur. Such frictionalcomponents may be of low cost relative to other components of therollers, and may assist in reducing and/or minimizing the cost ofmaintaining the rollers at a proper performance level, given that acertain level of wear may be anticipated and planned for.

Edge-Cleaning Support Roller

FIG. 6A is a side elevational view of an inventive support roller 601,shown adjacent to a wafer W and in contact with the cylindrical edgesurface 39 of the wafer W. The support roller 601 comprises acylindrical frictional surface 603, e.g., comprising polyurethane orsome other suitable frictional material, adapted to achieve frictionalcontact with the cylindrical edge surface 39 (FIG. 3A) of the wafer W,as shown in FIG. 6A. The support roller 601 is adapted, via suchfrictional contact, to support and/or rotate the wafer W.

In operation, the edge of the wafer W may be introduced between firstand second guide surfaces 605, 607 of the support roller 601, which maycomprise low-friction, low-wear material such as virgin PTFE toencourage sliding communication with the edge of the wafer W down theslopes of the guide surfaces 605, 607 toward the cylindrical frictionalsurface 603. Once frictional contact is established between thecylindrical frictional surface 603 of the support roller 601 and thecylindrical edge surface 39 of the wafer W, the support roller 601 maybe used to rotatably support and/or drive the wafer W. As describedabove, the cylindrical frictional surface 603 of the support roller 601may also be used to clean the wafer W's cylindrical edge surface 39,e.g., via rubbing contact caused by unmatched speeds of rotation.

FIG. 6B illustrates a particular embodiment of the support roller 601 ofFIG. 6A (support roller 601 a), shown in an exploded assemblyperspective view. As shown in FIG. 6B, the cylindrical frictionalsurface 603 of the support roller 601 a may comprise a portion of afriction disk 609, which may be of a simple, low-cost design adapted tominimize cost of replacement.

The support roller 601 a may further comprise a main body 611, of whichthe second guide surface 607 may comprise a part, and an end portion613, of which the first guide surface 605 may comprise a part. Thefriction disk 609 may be adapted to fit between the main body 611 andthe end portion 613, and the assembly may be adapted to be secured suchthat the friction disk 609 rotates along with the main body 611 and theend portion 613.

The support roller 601 a may still further comprise a channel 615 (FIG.6A) comprising first and second sides 617, 619 (FIG. 6A) for retainingthe edge of the wafer during rotational support thereof (e.g., byforming an “edge-trap” for retaining the edge of the wafer that includesthe frictional surface 603 (FIG. 6B)). In the embodiment of FIG. 6A, thefrictional surface 603 may form a transverse frictional surface that isadapted to contact the edge of the wafer and resist slidingthereagainst. The channel 615 may be straight, i.e., the first side 617and the second side 619 of the channel 615 may be arranged so as not toform a V, unlike the first inclined surface 23 and the second inclinedsurface 25 of the edge-cleaning roller 21 of FIG. 3A. Additionally, anoffset may be established between the first side 617 and the second side619 of the channel 615 that is sufficiently large to permit insertion ofthe edge of the wafer W, which may have, for example, a nominalthickness of 0.030 inches, and yet is sufficiently small so as toprevent tilt in the wafer W during rotation of the same, e.g., vialow-friction contact between the first side 617 of the channel 615 andthe first edge-adjacent region 41 (FIG. 3A) of the wafer W and/orbetween the second side 619 of the channel 615 and the secondedge-adjacent region 45 (FIG. 3A) of the wafer W.

Edge-Cleaning Side-Contact Roller

FIG. 7A is a side elevational view of an inventive side-contact roller701, shown adjacent to a wafer W. The side-contact roller 701 comprisesa first frictional planar surface 703, e.g., comprising polyurethane orsome other suitable frictional material, adapted to achieve frictionalcontact with the first edge-adjacent region 41 (FIG. 3A) of the wafer W.The side-contact roller 701 may additionally comprise a secondfrictional planar surface 705, similar to the first frictional planarsurface 703, and adapted to achieve frictional contact with the secondedge-adjacent region 45 (FIG. 3A) of the wafer W. The first frictionalplanar surface 703 and the second frictional planar surface 705 maycomprise sides of a straight channel 707, e.g., similar to thatdescribed above with reference to FIG. 6B, such that the edge of thewafer W may be accommodated between the channel sides, and tilt in thewafer W may be prevented. The side-contact roller 701 is adapted torotate the wafer W via frictional contact between the frictional planarsurfaces of the side-contact roller 701 and the edge-adjacent regions ofthe major surfaces of the wafers.

In operation, the edge of the wafer W may be introduced between firstand second guide surfaces 709, 711 of the side-contact roller 701, whichmay comprise a low-friction, low-wear material such as virgin PTFE toencourage sliding communication with the edge of the wafer W down theslopes of the guide surfaces 709, 711 toward the channel 707 of theside-contact roller 701. Once the edge of the wafer W has been insertedinto the channel 707, e.g., between the first frictional planar surface703 and the second frictional planar surface 705, a vertical gap 713 maybe maintained between the cylindrical edge surface 39 (FIG. 3A) of thewafer W and a corresponding portion of the side-contact roller 701 torestrict contact between the side-contact roller 701 and the wafer W tothe frictional “side” contact described above (i.e., at theedge-adjacent regions of the wafer's major surfaces), which frictionalcontact may be employed to drive the wafer W. Specifically, the wafer Wmay be vertically supported by other rollers (not shown) that preventthe wafer W from fully descending into the channel 707. As describedabove, the first frictional planar surface 703 and the second frictionalplanar surface 705 of the side-contact roller 701 may also be used toclean the edge-adjacent regions of the wafer's major surfaces, e.g., viarubbing contact.

FIG. 7B illustrates a particular embodiment of the side-contact roller701 of FIG. 7A (side-contact roller 701 a), shown in a cross-sectionalview. As shown in FIG. 7B, the first frictional planar surface 703 ofthe side-contact roller 701 a may comprise a portion of a first frictionring 715, which may be of a simple low-cost design adapted to minimizecost of replacement. Also, as shown in FIG. 7B, if the side-contactroller 701 a includes a second frictional planar surface 705, the secondfrictional planar surface 705 may comprise a portion of a similar secondfriction ring 717.

The side-contact roller 701 a may further comprise a hub 719, a firstguide ring 721 mounted on the hub 719 of which the first guide surface709 may comprise a part, and a second guide ring 723 mounted on the hub719 of which the second guide surface 711 may comprise a part. The firstfriction ring 715 and the second friction ring 717 may also be mountedon the hub 719, e.g., between the first guide ring 721 and the secondguide ring 723 as shown. An assembly may be formed thereby in which allcomponents rotate in unison.

Wafer Cleaning Apparatus Including the Above Inventive Rollers

One or more edge-cleaning rollers of FIGS. 4 and 5A-B, and one or moreof the frictional rollers of FIGS. 6A-B and 7A-B may be incorporatedwithin a wafer cleaning apparatus (not separately shown) utilizingscrubber brushes to clean major surfaces of a wafer in a manner similarto that of the scrubber mechanism of FIG. 2. Such a mechanism can takemany forms and/or perform many functions, including:

-   -   (1) comprising separate drive motors for the edge cleaning        roller and the other frictional rollers, e.g., so as to        facilitate an angled plane of rotation for the edge-cleaning        roller;    -   (2) comprising a toggle enabling the edge-cleaning roller to        switch between a mode in which it either lags behind or exceeds        the speed of rotation of the wafer edge so as to slide against        the wafer edge when in contact with it, and a mode in which it        matches the wafer edge speed and therefore does not slide        thereagainst when contacting the same;    -   (3) allowing the angle between the plane of rotation of the        edge-cleaning roller and the plane of rotation of the wafer to        be selectively varied;    -   (4) permitting the edge cleaning roller to toggle between        speed-matching and speed-lagging or speed-exceeding modes while        other frictional rollers remain in a speed-matching mode;    -   (5) the toggle of (2) above comprising a clutch that engages for        speed-exceeding or speed-lagging and disengages for speed        matching; and/or    -   (6) the toggle of (2) above comprising a friction brake that        engages for speed-lagging and disengages for speed matching.        Other configurations are also permissible.

The foregoing description discloses only exemplary embodiments of theinvention. Modifications of the above disclosed apparatus and methodswhich fall within the scope of the invention will be readily apparent tothose of ordinary skill in the art. For instance, according to one ormore embodiments, such as shown in FIG. 8, an edge cleaning roller 801may be provided having a plane of rotation 803 at an inventive angledorientation to the plane of rotation 805 of the wafer W, e.g., asdescribed by an angle 807, such that the plane of rotation 803 of theroller 801 intersects the plane of rotation 805 of the wafer W along aline (not separately shown) extending generally tangentially to thewafer W (e.g., as opposed to extending generally radially from thecenter of the wafer W as in the embodiment of FIG. 4). Such anarrangement permits the creation of multiple wear sectors on a singleinclined surface of the roller 801 by permitting removal, inversion, andreinstallation of the same roller 801 midway through a useful life thatmay be twice that of a conventionally oriented roller. This may bepossible, for example and as is apparent from FIG. 8, since each edgecorner tends to produce a wear sector at a unique location along theslope of a given inclined surface of the roller 801, such that inversionand reinstallation of the roller exposes unworn or “fresh” frictionsurfaces to each of the edge corners. In other embodiments, such asshown in FIG. 9, multiple edge-cleaning rollers 801 may be inventivelyoriented at one of two preferably equal and opposite angles to the planeof rotation of the wafer W, e.g., for balancing of out-of-plane forcesimparted to the wafer W by the angled rollers.

Finally, it should be understood that the inventive edge cleaningrollers described herein are each independently inventive, and may beemployed in apparatuses other than those adapted to scrub a wafer'smajor surface. Further, as will be apparent to those of ordinary skillin the art, the inventive rollers may be employed to clean the edge of awafer supported in any orientation (e.g., horizontal, vertical, etc.).Thus the inventive edge cleaning rollers may be advantageously employedin a vertically-oriented scrubber such as that disclosed in U.S. Pat.No. 6,575,177, the entire disclosure of which is incorporated herein bythis reference.

Accordingly, while the present invention has been disclosed inconnection with exemplary embodiments thereof, it should be understoodthat other embodiments may fall within the spirit and scope of theinvention, as defined by the following claims.

1. A support roller for supporting a rotating wafer within a wafercleaner, comprising: a guide portion, for receiving an edge of a wafer,having an inclined surface comprising a low-friction material andadapted to allow the wafer edge to slide thereagainst; and an edge-trapportion for retaining the edge of the wafer and having a transversesurface comprising a high-friction material and adapted, when incommunication with the edge of the wafer, to resist slidingthereagainst.
 2. The support roller of claim 1, wherein the edge-trapportion comprises a slot having a bottom comprising the transversesurface.
 3. The support roller of claim 2, wherein the slot comprisesslot walls located at opposite sides of the transverse surface, eachslot wall having a substantially straight portion.
 4. The support rollerof claim 3, wherein the substantially straight portions are parallel toeach other.
 5. The support roller of claim 1, wherein the transversesurface is cylindrical.
 6. The support roller of claim 1, wherein thetransverse surface comprises a frictional insert adapted to beincorporated within the roller.
 7. The support roller of claim 6,wherein the frictional insert is adapted to rotate with the supportroller.
 8. The support roller of claim 1, wherein the edge of the waferis a cylindrical edge surface positioned between a first and second edgeof the wafer.
 9. The support roller of claim 1, wherein the transversesurface is adapted to clean the edge of the wafer.
 10. The supportroller of claim 1, wherein the edge-trap portion is adapted to preventthe wafer from tilting during rotation.
 11. A side-contact roller forcontacting one or more major surfaces of a wafer rotating within a wafercleaner, comprising: a first frictional planar surface adapted toachieve frictional contact with a first edge-adjacent region of a firstmajor surface of the wafer; a second frictional planar surface adaptedto achieve frictional contact with a second edge-adjacent region of asecond major surface of the wafer; and wherein the first and secondfrictional planar surfaces form the sides of a channel, such that anedge of the wafer may be accommodated between first and secondfrictional planar surfaces.
 12. The side-contact roller of claim 11,wherein the side-contact roller is adapted to rotate the wafer viafrictional contact between the channel sides and the edge-adjacentregions of the wafer.
 13. The side-contact roller of claim 12, whereinthe channel sides are adapted to prevent the wafer from tilting duringrotation.
 14. The side-contact roller of claim 11, further comprising aguide portion, for receiving an edge of a wafer, having an inclinedsurface comprising a low-friction material and adapted to allow thewafer edge to slide thereagainst.
 15. The side-contact roller of claim11, further comprising a cylindrical edge surface disposed between thefirst and second frictional planar surfaces.
 16. The side-contact rollerof claim 15, wherein a gap is maintained between the cylindrical edgesurface of the side-contact roller and a corresponding cylindrical edgesurface of the wafer.
 17. The side-contact roller of claim 11, whereinthe first and second frictional planar surfaces are adapted to clean theedge-adjacent regions of the first and second major surfaces of thewafer.
 18. A method for supporting a wafer comprising: introducing anedge of the wafer between a first and second guide surface of aside-contact roller; and contacting edge-adjacent regions of the waferwith a first and second frictional planar surface of the side-contactroller.
 19. The method of claim 18 further comprising: rotating thewafer via the side-contact roller.
 20. The method of claim 18 furthercomprising: cleaning the edge-adjacent region of the wafer with thefirst and second frictional planar surfaces of the side-contact roller.